Braz Dent J 23(2) 2012
Braz Dent J (2012) 23(2): 160-166
M.S.C. Alves et al.
Bariatric surgery is currently the only effective
treatment for morbidly obese patients as it achieves
significant and sustained weight loss for millions
of individuals who suffer from morbid obesity. The
present popular operative procedures are all relatively
safe and efficient. However, all these procedures alter
anatomy and physiology of the gastrointestinal tract to
variable degrees (1). Therefore, surgery is not the final
step of obesity treatment, but it is rather the beginning
of a 1-2-year period of changes in behavior, diet and
physical activity followed by regular follow-up of a
multidisciplinary team of health professionals (2). The
Tooth Wear in Patients Submitted to
Maria do Socorro Coêlho ALVES1
Fernando Alberto Costa Cardoso da SILVA2
Stephanie Gomes ARAÚJO1
Antônio Cláudio Almeida de CARVALHO3
Alcione Miranda SANTOS4
Andrea Lúcia Almeida de CARVALHO5
1Dental School, UFMA - Federal University of Maranhão, São Luiz, MA, Brazil
2University Hospital, UFMA - Federal University of Maranhão, São Luís, MA, Brazil
3Brazilian Agricultural Research Agency, Macapá, AP, Brazil
4Department of Public Health, UFMA - Federal University of Maranhão, São Luiz, MA, Brazil
5Department of Dentistry, Dental School, UFMA - Federal University of Maranhão, São Luiz, MA, Brazil
Bariatric surgery may cause frequent vomiting episodes and gastroesophageal reflux, which promote the contact of gastric acids with
the teeth leading to irreversible loss of tooth structure. The aim of this study was to assess prevalence of tooth wear in bariatric patients.
One hundred and twenty-five patients were examined at a Public Hospital in São Luis, MA, Brazil, between July and October 2010,
being patients who had already been submitted to the bariatric surgery at least 6 months previously (Bariatric group), morbidly obese
patients who were on the waiting list for this surgery (Obese group) and patients who were waiting for ambulatory medical care in other
sectors (Control group). The patients answered an investigative questionnaire and were clinically examined using the Basic Erosive
Wear Examination (BEWE) scoring system, which allows the classification of the severity of noncarious dental lesions (NCDL) and
evaluation of risk. All patients presented some degree of tooth wear at different levels. However, the presence of NCDL was associated
with the group to which the patient belonged. The bariatric patients showed higher prevalence and a statistically significant level of
risk with regard to NCDLs when compared with the other patients, followed by the obese and control groups. Reflux and vomiting
did not seem to influence NCDL positively.
Key Words: Bariatric surgery, tooth wear, oral health.
alterations in the gastrointestinal shape and function
associated with the postoperative dietary changes
make these patients vulnerable to a series of potential
complications, such as abdominal pain, gallbladder
disease (biliary calculi), intestinal obstruction, peptic
ulcer, gastroesophageal reflux, nausea and vomiting
The gastroesophageal reflux disease (GERD), a
condition of high and rising incidence, may manifest
itself by typical (pyrosis and regurgitation) and
atypical (pulmonary, otorhinolaryngological and oral
problems) symptoms. Patients with GERD present a
higher incidence of dental erosion, aphthas, burning
mouth sensation, tooth sensitivity and a sour taste in
Correspondence: Profa. Dra. Maria do Socorro Coêlho Alves, Avenida Avicênia, Condomínio Green Village, casa 24, Calhau, 65071-370 São Luís,
MA, Brasil. Tel.: +55-98-3235-9981/9116-1144. Fax: +55-98-3235-9981. e-mail:email@example.com
Braz Dent J 23(2) 2012
Tooth wear of bariatric patients
the mouth (3,4).
Studies relate eating disorders (bulimia) to
episodes of vomiting, oral cavity implications, among
them, tooth wear (5,6).
The etiology of tooth wear is multifactorial and
it may result in the 3 following processes: abrasion
(wear caused by the interaction between teeth and
other materials), attrition (wear caused by tooth-to-
tooth contact) and erosion (dissolution of dental hard
tissues due to acid substances). An additional process
(abfraction) may accentuate wear by abrasion and/or
erosion. Clinical and experimental observations show
that individual tooth wear rarely occurs alone, but they
interact one with the other. This interaction seems to be
the main factor for tooth wear (7). Due to the nature of
this phenomenon, these lesions may lead to significant
oral health consequences. Dental tissue loss may result in
sensitivity, pulp necrosis, pain, loss of vertical dimension
and an unpleasant appearance (8).
Data referring to the oral health condition and
gastric reduction surgery are still scarce. A study in
Jerusalem with 113 patients found high tooth sensitivity
after bariatric surgery (9).
Since bariatric surgery can cause frequent
episodes of gastroesophageal reflux and vomiting,
promoting contact of the teeth with gastric acids, an
investigation was considered necessary. The aim of this
study was to determine prevalence of tooth wear as well
as the level of risk in a sample of bariatric patients from
a Brazilian public hospital.
MATERIAL AND METHODS
A sample selected from the University Hospital of
Federal University of Maranhão (UH-FUMA), located
in the city of São Luís, MA, Brazil, participated in this
cross-sectioned epidemiological study. The participants
were divided into 3 groups: the Bariatric group was
composed of patients who had been submitted to bariatric
surgery at least 6 months previously; the Obese group
was composed of patients on the waiting list for this
surgery; the Control group was composed of patients
from other sectors of the same hospital who were waiting
for an ambulatory medical care. All patients who agreed
to participate signed an informed consent form and the
research protocol was approved by the Ethics Committee
of the above-mentioned hospital (report #149/2010),
in accordance with resolution 196/96 of the Brazilian
National Health Council.
One hundred and thirty-nine patients accepted
to participate in the study. Fourteen patients who did
not meet the inclusion criteria were excluded from
the research. The exclusion criteria were as follows:
patients with debilitating systemic conditions and active
periodontal disease, seniors over the age of 70, children
and pregnant women; patients who underwent selective
wear and dental bleaching; complete denture wearers,
and individuals with removable orthodontic appliances.
Patients included in the study were between the ages of
16 and 70, totaling 125 participants.
Before collecting the clinical data, the examiner
was trained and intra-examiner agreement was verified
by the Kappa index. For this step of the study, 20
patients were examined at two distinct time periods
with an interval of 15 days, reaching the Kappa value
of 0.9 which is considered excellent since this value is
greater than 0.85.
The data collection instruments were the dental
examination and the investigative questionnaire.
All teeth between the second molars, including
these, were examined in both dental arches for the
presence or absence of noncarious lesions.
A recently proposed tooth wear index for
classification of the severity of tooth wear or tooth erosion
in studies of prevalence and incidence was used. This
index, called Basic Erosive Wear Examination (BEWE)
was designed to provide a simple and reproducible
scoring system (10), appropriate for screening. The
four- level score (Table 1) grades the appearance or
severity of wear on the teeth from no surface loss (0),
initial loss of enamel surface texture (1), distinct defect,
hard tissue loss (dentin) less than 50% of the surface
area (2) or hard tissue loss more than 50% of the surface
area (3). Buccal, occlusal, lingual and palatal surfaces
of all teeth in each sextant were examined, but only the
score of the tooth surface that showed the highest value
was recorded (10).
From the scores obtained in each sextant, the
cumulative sum was performed and therefore, a total
score of the level of risk for tooth wear of each patient
was obtained. Risk is understood as the probability of
the occurrence of an unfavorable event. No risk (below
or equal to 2), low risk (between 3 and 8), medium risk
(9 to 13) and high risk (14 or above) (Table 2).
The the term noncarious dental lesions (NCDL)
Braz Dent J 23(2) 2012
162M.S.C. Alves et al.
was used to indicate the prevalence of tooth wear.
In the investigative questionnaire, the socio-
demographic data of the patient (name, age, sex,
education, occupation, income, color/race self-
designation) and data collection of the patient’s family
income based on the income of minimum wages of those
responsible for providing for the family were obtained.
Therefore, the patients selected the correspondeing
monthly income, based on the value of the present
minimum wage (R$ 510,00), from the following options:
up to 1 minimum wage; from 1 to 2 minimum wages,
from 2 to 3; from 3 to 5; from 5 to 10; and above 10.
Information on the systemic conditions, such as self-
reported gastroesophageal reflux and vomiting episodes,
were also collected.
The collected data were entered and analyzed
in STATA 10.0 (Stata Corp LP, College Station, TX,
USA). There has been a descriptive analysis by means
of absolute and relative frequencies. Chi-Square and
Fisher’s Exact test was used to compare the study groups
with respect to some qualitative variables. A significance
level of 5% was considered for all analyses.
A total of 125 individuals were assessed, of which
41 (32.80%) were bariatric patients, 42 (33.60%) were
morbidly obese patients and 42 (33.60%) were control
patients. The socio-demographic characteristics of
the sample are summarized in Table 3. Regarding the
number of individuals assessed per group, the variables
sex, smoking, educational level (years) and ethnicity
showed homogeneous proportions with no statistically
significant differences among the groups (p>0.05).
The proportion of women was higher in the 3 groups.
However, the groups differed significantly with respect
to economic classification and mean age (p<0.05).
NCDL Evaluation per Patient
All patients presented some degree of tooth wear
at different levels. However, the presence of NCDL was
associated with the group to which the patient belonged.
The Bariatric group showed the highest prevalence
of NCDL (97.56%). This result was similar when the
Bariatric group was compared with the Obese group (40
patients or 97.56% vs. 35 patients or 83.33%, p=0.031)
and with the Control group (40 patients or 97.56% vs.
26 patients or 61.90%, p<0.001). A higher frequency
of NCDL was also found when the Obese group was
compared with the Control group (35 patients or 83.33%
vs. 26 patients or 61.90%, p=0.024) (Fig. 1).
Risk Level of NCDL per Patient
The highest percentage of patients with no risk
was found in the Control group (23.82%) followed by
the Obese group (7.14%). In the Bariatric group, all
patients presented some level of risk. However, when
the Bariatric group was compared with the Obese group
(0.00% vs. 7.14%, p=0.125), no significant difference
was found. The highest proportion
of low risk was found in the Control
group (64.28%) with a significant
difference from the Bariatric
group (p=0.002). When the Obese
and Bariatric groups (61.91% vs.
31.71%, p=0.003) were compared,
the Obese group showed a higher
proportion of NCDL, but such a
Table 1. Criteria for classifying tooth wear or dental erosion
according to the Basic Erosive Wear Examination scoring system.
ScoreCriteria for wear classification
0 No loss of surface
1Initial loss of surface texture
Distinct defect, hard tissue loss
<50% of the surface area
3Hard tissue loss ≥50% of the surface area
Score 1: slight wear; Scores 2 and 3: Dentin is frequently involved
(noncarious dental lesions), representing moderate and severe
lesions, respectively. Source: Adapted from Bartlett et al. (2008).
Table 2. Calculation of total score and risk level based on the Basic Erosive Wear
Examination scoring system.
Source: Adapted from Bartlett et al. (2008).
Braz Dent J 23(2) 2012
Tooth wear of bariatric patients
difference was not found between the Control and Obese
groups (Table 4).
The Bariatric group showed the highest percentage
of medium risk (63.41%). A statistically significant
difference was found between the Bariatric and Obese
group (63.41% vs. 30.95%, p=0.003) and between
the Bariatric and Control group (63.41% vs. 11.90 %,
p<0.001). A high level of risk was found in the Bariatric
group (4.88%), though not statistically significant.
Reflux and Vomiting
With regard to the self-reported gastroesophageal
reflux, the Bariatric group obtained the highest
statistically significant occurrence when compared with
the Obese group (63.41% vs. 28.57%, p=0.001) and
Control group (63.41% vs. 2.38 %, p<0.001); whereas in
the Obese group, a significantly higher percentage was
found in comparison with Control group (28.57% vs. 2.38
%, p=0.001). Regarding self-reported vomiting episodes,
the Bariatric group showed a higher percentage than the
Obese group (60.98% vs. 14.28%, p<0.001) and Control
group (60.98% vs. 2.38%, p<0.001); when comparing the
obese and Control groups (14.28% vs. 2.38%, p=0.048),
a statistically significant higher percentage was found
in the Obese group (Table 5).
Table 3. Frequency of the socio-demographic characteristics of 125 patients of the UH- FUMA.
Bariatric (n=41) Obese (n=42) Control (n=42)
38 92.6835 83.333583.33
Men3 7.327 16.677 16.67
42.707 (9.450) 36.523 (10.177) 33.380 (9.985)
39 95.124197.62 38 90.48
Yes2 4.871 2.3849.52
13 31.718 19.051126.19
Class B 2048.78 14 33.33 10 23.81
Class C, D and E8 19.512047.62 2150
Educational level (years)
2 4.884 9.523 7.14
4-94 9.76 11 26.19 1433.33
≥1035 85.362764.28 2559.52
1331.71 1228.57 1023.81
Mulatto20 48.782457.14 2252.38
Symbol indicates statistically significant differences (Chi-square and Fisher’s exact tests, p<0.05).
Braz Dent J 23(2) 2012
164 M.S.C. Alves et al.
The Bariatric group differed significantly from the
other groups and had the highest prevalence of NCDL,
reflux and vomiting. However, reflux and vomiting did
not seem to influence NCDL positively (p>0.05).
There is currently an increasing interest in
NCDL. Epidemiological studies have shown results
for prevalence ranging from 5% to 85%, irrespective
of the type and etiology of these lesions (7,11,12).
Differences in the prevalence data among the studies
may be explained due to the different diagnostic criteria
and indexes used (10). In this study, the BEWE scoring
system was used, which was suitable for epidemiological
and clinical trials because it has fewer categories and
therefore, it is easier to memorize, enabling
good examiner training (Kappa = 0.9), as
reported elsewhere (12).
There has not yet been evidence
that income contributes to the appearance
of NCDL, for studies have shown
contradictory results. It is understood
that low income influences educational
level, oral hygiene and diet habits and
that a higher educational level provides
more knowledge about general health
and oral care (13). However, tooth wear
has been found to be prevalent in children
whose families have a higher income
when compared with families who have
a lower income (14). In the sample of
this research, a difference in the 3 groups
with regard to monthly income was
found, but the educational level showed a
homogeneous proportion (most had high
school education). The Bariatric group,
had the highest monthly income (most
patients from classes A and B), but also
Table 4. Distribution of level of risk of NCDL in bariatric, obese
and control patients.
Total 4110042100 42100
Different letters in the same line indicate statistically significant
differences (Chi-square and Fisher’s Exact tests, p<0.05).
Table 5. Distribution of the presence of gastroesophageal reflux
and vomiting in bariatric, obese and control patients.
Bariatric (41)Obese (42)Control (42)
No 15 36.583071.43 4197.62
No1639.02 3685.71 4197.62
GERD: Gastroesophageal reflux disease. Different letters in
rows indicate statistically significant differences (Chi-square and
Fisher’s Exact tests, p<0.05).
Figure 1. Prevalence of noncarious dental lesions in the bariatric, obese and
control patients of the UH-FUMA. NCDL. Yes - (score 2 + score 3), that is,
pathological wear. No - (score 1), physiological wear. Different letters indicate
statistically significant differences (Chi-square and Fisher’s exact tests, p<0.05).
Braz Dent J 23(2) 2012
Tooth wear of bariatric patients
showed the highest prevalence of NCDL.
The pathogenesis of tooth wear was discussed
throughout the past century and there are still controversy
and incoherences. Human teeth are subjected to constant
physiological wear during the individual’s entire life
and this phenomenon is probably related to age (15).
Thus, in this study, the presence of enamel wear was
also common to all volunteers, which is in agreement
with the above-mentioned research (16). However,
severe degrees of wear were observed in different age
groups, which could be caused irrespective of age (15)
and may even lead to complete destruction of teeth (8).
The highest prevalence of NCDL (score 2 and
score 3) found in this research occurred in the Bariatric
group with a percentage of 97.56%, a higher frequency
than the one found in the literature. It is believed that this
high prevalence was due to the sample being composed
of individuals who could have been more exposed to
agents that cause these lesions. Another result that is a
matter of concern refers to the Obese group in which
83.33% of patients presented moderate and severe dental
lesions, leading to the assumption that it is believed
that NCDL in morbidly obese patients may progress to
higher levels if there is no intervention, as those observed
in patients who have undergone bariatric surgery. The
development of NCDL is a gradual and variable process
that requires analysis of each case in particular to prepare
a treatment plan and provide guidance on the patient’s
diet and habits. Prevention would be the most efficient
and relevant manner to prevent the appearance of lesions
as well as their progression when it is already existent
and prevention is indicated for the general population.
However, some authors (10) recommend that dentists
who have patients with high and medium risk, as well
as bariatric patients, in addition to the procedures
described previously, should identify the etiology of
wear, use fluoride to increase resistance of the tooth
surface, monitor study models, photographs and clinical
examinations in a time interval of 6 to 12 months, to
evaluate, in special cases of severe progression, the need
for restoring the teeth.
At present, lifestyle creates nutritional conditions
that are potentially dangerous for oral health. Patients,
who have undergone gastric reduction surgery and do
not adapt themselves to the new dietary habits, may
present gastroesophageal disturbances. It was found that
the highest frequency of reflux and vomiting episodes
(63.41% and 60.98%, respectively) occurred in the
Bariatric group. However, irrespective of the group
(Bariatric, Obese and Control), no association between
reflux, vomiting and NCDL was found in this study.
This result was also found for patients with reflux (17).
Contrary to these findings, other studies (4,6) observed
association between reflux, vomiting and NCDL in
the general population. This difference in results may
be related not to the difference, but to the frequency
of reflux and vomiting in each patient, which was not
investigated in the present study. Other factors have
been investigated and a significant correlation between
NCDL and toothbrushing more than once a day with
a medium or hard toothbrush, vegetarian diets and
self-reported intake of citrus fruit, sodas, vinegar used
in spices, alcohol, yoghurt, vitamin C and carbonated
beverages (18,19) were found. Most authors agree that
the cause is multifactorial and it is difficult to attribute
a primary etiological factor. Therefore, a cumulative
effect probably occurs from many etiological factors
This is the first study that has assessed prevalence
of tooth wear in bariatric, obese and control patients
in Brazil concomitantly and a high, medium and low
prevalence was found, respectively. These frequent
occurrences should not be ignored and they have become
a public health problem, as NCDL are not only an esthetic
problem, but a functional problem with the possibility
of causing dental loss. Therefore, health teams need to
consider potential dental problems after this surgery and
provide their patients with information and appropriate
instructions, in addition to regular monitoring of teeth
by a dentist. The oral health is inseparable from the
overall health of the individual, dental care is essential
and necessary to improve the quality of life.
The following factors were a limitation of the
research, as they were not considered in the present study:
diet, oral hygiene, periodontal and occlusion condition,
habits such as bruxism, and quality and quantity of saliva,
which may contribute to tooth wear. The clinical criteria
of the BEWE could be accompanied by a group of dietary,
behavioral and biological criteria (21). In addition,
this study only analyzed the number of non-restored
lesions and consequently, the data do not represent the
number of lesions since they could have been restored
or teeth could have been extracted. However, the results
of this study show the importance of a preventive
approach of the most susceptible groups, as in the case
of bariatric patients, as these lesions could have been
avoided through continuous control. Furthermore, it was
found that the Obese group was second in prevalence,
Braz Dent J 23(2) 2012
166 M.S.C. Alves et al.
being higher than in the Control group. This is equally
important since obesity is a major public health problem
affecting millions of people worldwide. As this was
preliminary investigation, further studies are needed,
especially prospective studies.
In conclusion, the bariatric patients showed the
highest prevalence and level of risk with regard to NCDL
when compared with the morbidly obese and control
patients. However, reflux and vomiting did not seem to
influence the appearance of NCDL positively.
Cirurgia bariátrica pode provocar freqüentes episódios de vômito
e refluxo gastroesofágico o que promove o contato dos ácidos
gástricos com os dentes fazendo que haja perda irreversível
de estrutura dental. Este estudo teve como objetivo avaliar a
prevalência de desgaste dentário em pacientes bariátricos. Foram
examinados 125 pacientes em um Hospital Público de São Luís,
MA no período de julho a outubro de 2010, distribuídos em
pacientes que já tinham sidos submetidos à cirurgia bariátrica
há pelo menos 6 meses (Grupo bariátrico), obesos mórbidos
que estavam na lista de espera para esta cirurgia (Grupo obeso)
e por pacientes que esperavam por consulta médica ambulatorial
em outros setores (Grupo controle). Os pacientes responderam a
um questionário investigativo e foram examinados clinicamente
utilizando o “Basic Erosive Wear Examination” - BEWE (Índice
Básico do Desgaste Erosivo) que permite a classificação da
severidade das lesões não-cariosas e avaliação de risco. Todos
os pacientes apresentaram algum grau de desgaste dentário em
diferentes níveis. No entanto, a presença de LDNC (lesão dental
não-cariosa) estava associada ao grupo que o paciente pertencia.
O grupo bariátrico apresentou maior prevalência e nível de risco
em relação às LDNC’s estatisticamente significante quando
comparado aos outros grupos, seguido pelo grupo de obeso e
controle. Refluxo e vômito parecem não influenciar positivamente
1. Shikora SA, Kim JJ, Tarnoff ME. Nutrition and gastrointestinal
complications of bariatric surgery. Nutr Clin Pract 2007;22:29-40.
2. Breznikar B, Dinevski D. Bariatric surgery for morbid obesity:
pre-operative assessment, surgical techniques and post-operative
monitoring. J Int Med Res 2009;37:1632-1645.
3. Corrêa MCCSF, Lerco MM, Henry MACA. Study in oral cavity
alterations in patients with gastroesophageal reflux disease. Arq
4. Moazzez, R, Bartlett D, Anggiansah A. Dental erosion, gastro-
oesofageal reflux disease and saliva: how are they related? J Dent
5. Aranha AC, Eduardo Cde P, Cordás TA. Eating disorders part
II: clinical strategies for dental treatment. J Contemp Dent Pract
6. Emodi-Perlman A, Yoffe T, Rosenberg N, Eli I, Alter Z, Winocur
E. Prevalence of psychologic, dental, and temporomandibular
signs and symptoms among chronic eating disorders patients: a
comparative control study. J Orofac Pain 2008;22:201-208.
7. Addy M, Shellis RP. Interaction between attrition, abrasion and
erosion in tooth wear. Monogr BucalSci 2006;20:17-31.
8. Yip KH, Smales RJ, Kaidonis JA. Differential wear of teeth and
restorative materials: clinical implications. Int J Prosthodont
9. Heling I, Sgan-Cohen HD, Itzhaki M, Beglaibter N, Avrutis O,
Gimmon Z. Dental complications following gastric restrictive
bariatric surgery. Obes Surg 2006;16:1131-1134.
10. Bartlett D, Ganss C, Lussi A. Basic Erosive Wear Examination
(BEWE): a new scoring system for scientific and clinical needs.
Clin BucalInvest 2008;12:S65-S68.
11. Levitch LC, Bader JD, Shugars DA, Heymann HO. Non-carious
cervical lesions. J Dent 1994;22:195-207.
12. Mulic A, Tveit AB, Wang NJ, Hove LH, Espelid I, Skaare AB.
Reliability of two clinical scoring systems for dental erosive wear.
Caries Res 2010;44:294-299.
13. Al-Dlaigan YH, Shaw L, Smith A. Dental erosion in a group
of British 14-year-old school children. Part I: prevalence and
influence of differing socioeconomic backgrounds. Br Dent J
14. Mangueira DF, Sampaio FC, Oliveira AF. Association
between socioeconomic factors and dental erosion in Brazilian
schoolchildren. J Public Health Dent 2009;69:254-259.
15. Bartlett D, Dugmore C. Pathological or physiological erosion - is
there a relationship to age? Clin Oral Invest 2008;12:S27-S31.
16. Fares J, Shirodaria S, Chiu K, Ahmad N, Sherriff M, Bartlett D.
A new index of tooth wear. Reproducibility and application to
a sample of 18-to 30-year-old university students. Caries Res
17. Di Fede O. Oral manifestations in patients with gastro-esophageal
reflux disease: a single-center case-control study. J Oral Pathol
18. Smith WA, Marchan S, Rafeek RN.The prevalence and severity
of non-carious cervical lesions in a group of patients attending a
university hospital in Trinidad. J Oral Rehabil 2008;35:128-134.
19. Torres CP, Chinelatti MA, Gomes-Silva JM, Rizóli FA, Oliveira
MA, Palma-Dibb RG, et al.. Surface and subsurface erosion
of primary enamel by acid beverages over time. Braz Dent J
20. El Aidi H, Bronkhorst EM, Huysmans MC, Truin GJ. Multifactorial
analysis of factors associated with the incidence and progression
of erosive tooth wear. Caries Res 2011;45:303-312.
21. Margaritis V, Mamai-Homata E, Koletsi-Kounari H,
Polychronopoulou A. Evaluation of three different scoring systems
for dental erosion: a comparative study in adolescents. J Dent
Received June 16, 2011
Accepted November 17, 2011